AJP - Gastrointestinal and Liver Physiology, Vol 265, Issue 6 1016-G1020, Copyright © 1993 by American Physiological Society
Effect of vagotomy on ornithine decarboxylase activity in rat duodenal mucosa
J. Tanaka, K. Fujimoto, T. Sakata, T. Fujimoto, S. Tsunada, R. Iwakiri, M. Yamaguchi, Y. Okabe and H. Yoshimatsu
Department of Internal Medicine, Saga Medical School, Japan.
The aim of this study was to determine whether the circadian rhythm of
ornithine decarboxylase (ODC) activity in rat small intestine is controlled
by factors other than luminal nutrients. ODC activity in duodenal and
jejunal mucosa of rats fed ad libitum was measured at four time points
(0500, 1100, 1700, 2300 h; light period: 0800-2000 h). ODC activity in the
jejunum increased in the dark period, which is when rats normally eat. In
contrast, ODC activity in the duodenum began to increase at 1700 h, which
is when rats do not normally eat, as indicated by the recorded feeding
pattern. The increase in ODC activity in the duodenum at 1700 h, but not at
other time points, was abolished by subdiaphragmatic vagotomy, whereas
vagotomy had no effect on the feeding pattern of rats. Subdiaphragmatic
vagotomy had no effect on ODC activity in the jejunum. ODC activity in the
duodenum increased following glycoprivation of the central nervous system
induced by infusion of 2-deoxyglucose into the third cerebroventricle.
These results indicate that the increase in duodenal ODC activity at 1700 h
is due to a signal from the upper brain structure through the vagal nerve
and not to luminal nutrient factors.
